Process for making gas and tar



Aug. 28, 1934. Y Q E;` EVANS l 1,971,710

XROCESS FOR MAKING GAS AND TAR Filed July l5, 1931 2 Sheets-Sheet l AIR 1s MME/wa@ fwn/Ess:

n" wen Evans /L-"f" 5:/

Aug- 28, 1934. o, B. EVANS 1,971,710

PROCESS FOR MAKING GAS AND TAR Patented Aug. Z8, 1934 1,911,111 rimesseI Foa MAKING Gas AND 'ma Owen B. Evans, Philadelphia, Pa., assignor to The- United Gas Improvement Company, Philadel- A phia, Pa., a corporation of Pennsylvania Applicationluly 15, 1931, Serial N0. 550,834

3 Claims.

The present invention relates to the manufacture of 'carburetted water gas. useful in the manufacture of carburetted water gas when employing heavy oils and residuums as 6 the carburetting material. These heavy oils and residuums on vaporization yield much larger quantities of carbon than ordinary gas oil. As an example of such oils mention may bemade of the so-called Bunker oils", as for instance Bunker C, which may be topped crude oils and may contain varying quantities of cracker tar.

These oils are preferably employed for car- 'buretting by vaporizing them on the top of the generator fuel bed and in an empty carburetter. It is desirable to vaporize as much of the oil as possible in the generator, as the liberated carbon is largely retained in the fuel bed and is utilized as fuel in the production of water gas. At present prices of heavy oil and coke in many localities, large economies result from increasing the quantity of oil used and decreasing the quantity of coke employed. t

The quantity of oil that may be vaporized during the uprun is limited and it is desirable to introduce oil during the down run or backrun also, passing the resulting oil vapors down through the fuel bed and cracking them there into oil gas and hydrogen, liberating further carbon, a large part of which is utilized as fuel.

In the manufacture of carburetted water gas, a considerable quantity of tar is produced which has a value dependent on its quality.

I have found that the tar produced when performing the above process is unsuited for certain utilizations. For instance in the manufacture of bituminous road compounds, water gas tar is employed but it is required to be of low free carbon content.

I have found when operating as above that the tar produced has too high a content of free carbon to be suitable for road compound material. I have further found that due to the high temperature and comparative severity of the cracking of the oil vapors in the fuel bed, the down run gas issuing from the fuel bed contains a larger quantity of entrained free carbon and a smaller quantity of tar than the uprun gas issuing from the superheater.

According to the present invention instead of following the present practice and condensing the tars from both the uprun and down run gas in the same vessel and simultaneously washing out with the tar, the entrained carbon, I treat the uprun and down run gas separately, segregating the comparatively small quantity of high free carbon con- It is particularly' tent tar which the down run gas contains, from the comparatively large quantity of low free carbon content tar contained in the uprun gas, thereby recovering in the segregated tar of the uprun gas a tar of much lower free carbon content than is produced by the mixture.

I may do this by conducting the uprun and. downrun gas to separate washboxes provided with separate tar disposal means, or I may conduct the above gases to 'the same washbox, washing the 65 downrun gas and precipitating its tar and carbon content prior to its arrival at the Washbox.

The invention will be further described in connection with the attached figures which form a part of this specification and in which.

Figure 1 shows in partial elevation and partial vertical cross section a carburetted water gas set equipped with a double Washbox having sections for the separate collection of uprun and down run tar.

Figure 2 shows in partial elevation and partial vertical cross section a carburetted water gas set equipped with a single washbox and with a washer arranged in the pipe between the base of the generator and the washbox.

Referring to Figure 1,

1 is the generator, 2 the carburetter, 3 the superheater of a carburetted water gas set. 4 is the ignited generator fuel bed, 5 an air supply means for blasting the fuel bed, 6 a steam supply 85 means for uprunning, and '7 an oil supply means for spraying oil onto the top of the fuel bed.

The generator is connected above the fuel bed with the carburetter 2 by connection 8. 9 is a supply of secondary air. l0 is an oil supply to the carburetter.

The carburetter communicates with the superheater 2 by connection 11. 12kL indicates the superheater checkerbrick. 13 is the stack valve. 14 is a steam supply means for down running.

The superheater is connected by a gas ofitake 15 provided with valve 16 with one section 1'7 of a double washbox. The generator below the fuel bed is connected by gas oiftake 18 provided with valve 19 to another section 20 of the double washbox. 21 indicates a partition between the sections.

22 is the gas offtake from the washbox section 17, 23`is the gas oiltake from washbox section 20, each leading into the pipe 24, provided with valve 25 and leading through accessory apparatus to storage.

Washbox section 17 is connected to the seal pot 26, which is provided with the tar offtake connection 27.

Washbox section 20 is connected to seal pot 28 provided with the tar offtake 29.

In operation of the apparatus of Figure 1, the following is an illustrative cycle.

The fuel bed is blasted with air supplied at 5 and the resultant blast gases burned in the carburetter and superheater with air supplied through 9. The burned gases issuing through stack valve 13, which is open.

After the air blasting operation the stack valve is closed, and with valves 16 and 25 open and valve 19 closed, an uprun is made with steam supplied through 6. 'Ihe resultant water gas is carburetted by admitting oil to the top of the fuel bed through 7 and to the carburetter through 10.

'Ihe water gas, with the oil vapors and oil gas, pass through the carburetter and superheater where the hydrocarbons are cracked to oil gas, tar vapors and carbon. The resultant carburetted water gas laden with tar vapors and with a relatively small quantity of entrained carbon passes through connection 15 to the washbox section 17 where the tar is condensed out, entrained carbon dropping out with it. The gas passed through connections 23, 24 and valve 25 to storage. The tar of relatively low carbon content flows to the seal pot 26 and through offtake 27 to disposal.

After the uprun, valve 16 is closed and valve 19 opened. A back' run is made with steam introduced at 14 and passed through the superheater and carburetter and down through the generator fuel bed, simultaneously oil is sprayed onto the top of the fuel bed through oil supply 7. The oil is vaporized on the top of the fuel bed, and the resultant oil vapors pass down through the fuel bed. Oil may be also vaporized in the carburetter and the resultant oil vapors passed down through the fuel bed or oil may be vaporized in the carburetter alone and the resultant oil vapors passed down through the fuel bed.

The hydrocarbons are cracked to oil gas containing a large quantity of hydrogen, a relatively small quantity of tar and a relatively large quantity of carbon, a considerable portion of which may be entrained in the Water gas issuing from the base of the generator. The water gas and cracked hydrocarbon gas, tar vapors, and entrained carbon pass through connection 18 to the washbox section 20, where the tar and carbon are thrown down, the gas passing through connections 23 and 24 and valve 25 to storage. The tar flows to seal pot 28 and by oitake 29 to a separate disposal from that to which the tar from seal pot 27 flows.

Referring to Figure 2,

3l is the generator, 32 the carburetter and 33 the superheater of a carburetted Water gas set. The generator is provided with an ignited fuel bed indicated at 34. 35 is an air blast supply means, 36 a steam supply means for uprunning, 37 is an oil supply means. Connection 38 leads to the carburetter. 39 is a supply of secondary air.

The carburetter is provided with oil supply means 40 and is connected with the superheater by connection 41.

The superheater is provided with checkerbrick indicated at 42. 43 is a stack valve. 44 is a steam supply means for down running. Connection 45 leads from the superheater by way of reversing valve 46 to the washbox 47.

The gas oitake 48 leads from the generator below the fuel bed to the washer 49. The washer may be provided with any suitable packing, as`

for instance grids indicated at 51 or may be empty. The washer is provided with scrubbing medium supply means illustrated at 52. Gas offtake 53 leads from the washer 49 through reversing valve 46 to the washbox 47. The washer 49 drains into the seal pot 54. 55 is the offtake for tar from the seal pot 54.

The washbox 47 is provided with'the gas oftake 56 provided with valve 57 and leading through auxiliary apparatus (not shown) to storage. Washbox 47 drains into seal pot 58. 59 indicates the tar run off to separate disposal from that to which oitake 55 leads.

In operation of the apparatus of Figure 2, the air blasting, steaming and carburetting steps may be conducted as described in connection with Figure 1, the reversal of the reversing valve 46 taking the place of the alternate operation of the separate valves in the oitakes from the generator and superheater in Figure 1. However, in Figure 2 the uprun and downrun gas are led to a common washbox 47.

The uprun gas passes directly through oftake 45 and valve 46 to the washbox, Where tar is precipitated which passes to the seal pot 58 and by oitake 59 to disposal. The downrun gas passes through the washer 49 before passing through valve 46 to the washbox 47. In the washbox the gas is scrubbed with any suitable scrubbing medium, for illustration water, and the entrained carbon in the gas is scrubbed out together with whatever tar it may contain.

The scrubbed gas passes to the Washbox 47 and therethrough without contaminating with its previous high entrained carbon content, the lower carbon content tar deposited from the uprun gas.

It is desirable to locate the washer as close to the generator as can be conveniently done, with a short connection between the generator and the washer. The washer, then prevents the clogging of the so called back run pipe with carbon and tar or pitch. The washing of the gas on the generator side of the valve controlling the flow also prevents the accumulation of carbon on the valve seats with consequent faulty operation of the valve.

The scrubbing of the down run reformed gas is desirable for this reason alone aside from the recovery of a better tar from the uprun gas, and in this connection if the market conditions do not make it undesirable, tar may be employed as a scrubbing medium for the washer.

Throughout this specification and claims the term gas making fluids" is used to include air, water, steam and liquid or gaseous hydrocarbons.

The term heat regenerating apparatus includes the carburetter and superheater whether constructed in separate shells, as shown, or in one shell or as part of the generator.

I do not intend to be limited in the practice l lo of my invention save as the scope of the prior art and of the attached claims may require.

I claim:

1. A process of manufacturing and of recovering tar from combustible gas as practiced in an apparatus including a generator containing an ignited fuel bed and a heat regenerating apparatus, said process including the following steps; manufacturing combustible gas containing low free carbon content tar by .vaporizing heavy oil in said generator and passing the resulting oil gas throughv said heat regenerating apparatus, and extracting said low free carbon content tar from said gas; another step being, manufacturing high free carbon content tar by introducing ing said high free carbon content tar from said gas separately from said low free carbon content tar.

2. A process of manufacturing and of recovering tar from combustible gas as practiced in an apparatus including a generator containing an ignited fuel bed and heat regenerating apparatus, which process includes the following steps: manufacturing gas containing low free carbon content tar by passing gas making uids successively through said fuel bed and through said regenerating apparatus, simultaneously Vaporizing heavy oil in said generator and passing the resulting oil gas together with the gas resulting from said gas making fluids through said regenerating apparatus, and condensing said low free carbon content tar from said gas; another step being, manufacturing gas containing high free carbon content tar by introducing gas making fiuidsto said regenerating apparatus, vaporizing heavy oil to oil gas, passing said oil gas and the gas resulting from said gas making fluid through said ignited fuel bed, and extracting said high free carbon content tar from said gas separately from said low free carbon content tar.

3. A process of manufacturing and of recovering tar from carburetted Water gas as practiced in a carburetted water gas set including a generator containing an ignited fuel bed and regenerating apparatus, said process including the following steps: manufacturing gas containing low free carbon content tar by making an uprun with steam through said ignited fuel bed and passing the resulting gas through said regenerating apparatus, simultaneously' vaporizing heavy oil and carburetting the water gas with the resulting oil gas, and extracting said low free carbon content tar from said carburetted water gas; another step being, manufacturing gas containing high free carbon content tar by making a back run with steam through said, regenerating apparatus and through said fuel bed, vaporzing heavy oil to oil gas, passing said oil gas together with said back run steam through said ignited fuel bed, and extracting said high free 'carbon content tar separately from said low free carbon content tar.

OWEN B. EVANS.

will 

